Rotary electric machine

ABSTRACT

A stator winding is configured by connecting a first three-phase stator winding and a second three-phase stator winding in parallel. A U 1 -phase winding of the first three-phase stator winding is configured by connecting a U 1-1 -phase winding portion and a U 1-2 -phase winding portion in series, and a U 2 -phase winding of the second three-phase stator winding is configured by connecting a U 2-1 -phase winding portion and a U 2-2 -phase winding portion in series. The U 1-1 -phase winding portion and the U 2-2 -phase winding portion are m-turn wave windings, and the U 2-1 -phase winding portion and the U 1-2 -phase winding portion are n-turn wave windings (where n does not equal m). The U 1-1 -phase winding portion and the U 2-1 -phase winding portion are mounted into a first slot group, and the U 1-2 -phase winding portion and the U 2-2 -phase winding portion are mounted into a second slot group.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotary electric machine such as anautomotive alternator, and particularly relates to a mountingconstruction for a stator winding that is wound into a wave winding in astator core in which slots are formed at a ratio of two slots per phaseper pole.

2. Description of the Related Art

In conventional rotary electric machines, a stator winding is configuredby wye-connecting a U-phase winding, a V-phase winding, and a W-phasewinding in each of which a first winding and a second winding that havea phase difference of 30 electrical degrees from each other areconnected in series, and the first winding and the second winding areeach configured by connecting a plurality of windings in parallel (seePatent Literature 1, for example).

Patent Literature 1: Japanese Patent Laid-Open No. 2010-136459 (Gazette:FIG. 15)

In conventional rotary electric machines according to Patent Literature1, because the plurality of windings that constitute the first windingand the second winding are concentrated windings, turn counts of thewindings can be changed easily. Thus, problems with cyclic currents inparallel circuit portions can easily be solved by making the turn countsof the plurality of windings that are connected in parallel equal. Inorder to achieve desired output characteristics, the turn count betweenthe first winding and the second winding that are connected in seriesmust also be changed, but that requirement can be met easily by changingthe turn counts of the windings that constitute the first winding andthe turn counts of the windings that constitute the second winding.

Even if the plurality of windings that constitute the first winding andthe second winding are constituted by wave windings instead ofconcentrated windings, problems with the generation of cyclic currentsin the parallel circuit portions can be solved by making the turn countsof the plurality of windings that are connected in parallel equal, andpredetermined output characteristics can be achieved by changing theturn counts between the first winding and the second winding that areconnected in series.

Now, let us assume that the first winding is configured by connectingtwo four-turn wave windings in parallel, and the second winding isconfigured by connecting two three-turn wave windings in parallel. Inthat case, eight conductor wires are housed in each of the slots inwhich the first winding is mounted, and six conductor wires are housedin each of the slots in which the second winding is mounted. Thus, thenumber of conductor wires that are housed in the slots is different ineach slot, and one disadvantage has been that unevenness occurs on theinner circumferential surfaces of the coil end groups of the statorwinding, generating loud wind-splitting noise with the rotor.

SUMMARY OF THE INVENTION

The present invention aims to solve the above problems and an object ofthe present invention is to provide a rotary electric machine in whichphase windings are configured by connecting in series two windingportions that have different turn counts to increase output, and inwhich the formation of unevenness on inner circumferential surfaces ofcoil end groups is suppressed to enable wind-splitting noise to bereduced.

In order to achieve the above object, according to one aspect of thepresent invention, there is provided a rotary electric machineincluding: a rotor that is rotatably supported by a housing; and astator including: a stator core in which slots are formed at a ratio oftwo slots per phase per pole; and a first three-phase stator winding anda second three-phase stator winding that are mounted into the statorcore, the stator being supported by the housing so as to surround therotor. The first three-phase stator winding is configured bywye-connecting a U₁-phase winding, a V₁-phase winding, and a W₁-phasewinding, and the second three-phase stator winding is configured bywye-connecting a U₂-phase winding, a V₂-phase winding, and a W₂-phasewinding. The U₁-phase winding is configured by connecting a U₁₋₁-phasewinding portion and a U₁₋₂-phase winding portion in series, the V₁-phasewinding is configured by connecting a V₁₋₁-phase winding portion and aV₁₋₂-phase winding portion in series, the W₁-phase winding is configuredby connecting a W₁₋₁-phase winding portion and a W₁₋₂-phase windingportion in series, the U₂-phase winding is configured by connecting aU₂₋₁-phase winding portion and a U₂₋₂-phase winding portion in series,the V₂-phase winding is configured by connecting a V₂₋₁-phase windingportion and a V₂₋₂-phase winding portion in series, and the W₂-phasewinding is configured by connecting a W₂₋₁-phase winding portion and aW₂₋₂-phase winding portion in series. The U₁₋₁-phase winding portion andthe U₂₋₁-phase winding portion are mounted into a first slot group thatis constituted by the slots at intervals of six slots, the U₁₋₂-phasewinding portion and the U₂₋₂-phase winding portion are mounted into asecond slot group that is constituted by the slots at intervals of sixslots and that is adjacent to the first slot group, the V₁₋₁-phasewinding portion and the V₂₋₁-phase winding portion are mounted into athird slot group that is constituted by the slots at intervals of sixslots, the V₁₋₂-phase winding portion and the V₂₋₂-phase winding portionare mounted into a fourth slot group that is constituted by the slots atintervals of six slots and that is adjacent to the third slot group, theW₁₋₁-phase winding portion and the W₂₋₁-phase winding portion aremounted into a fifth slot group that is constituted by the slots atintervals of six slots, and the W₁₋₂-phase winding portion and theW₂₋₂-phase winding portion are mounted into a sixth slot group that isconstituted by the slots at intervals of six slots and that is adjacentto the fifth slot group. The U₁₋₁-phase winding portion, the U₂₋₂-phasewinding portion, the V₁₋₁-phase winding portion, the V₂₋₂-phase windingportion, the W₁₋₁-phase winding portion, and the W₂₋₂-phase windingportion are configured by winding conductor wires that have an identicalcross-sectional shape into respective wave windings in the slots atintervals of six slots for m turns (where m is an integer), and theU₁₋₂-phase winding portion, the U₂₋₁-phase winding portion, theV₁₋₂-phase winding portion, the V₂₋₁-phase winding portion, theW₁₋₂-phase winding portion, and the W₂₋₁-phase winding portion areconfigured by winding the conductor wires into respective wave windingsin the slots at intervals of six slots for n turns (where n is aninteger that is different than m). The first three-phase stator windingand the second three-phase stator winding are connected in parallel byconnecting an output end of the U₁-phase winding and an output end ofthe U₂-phase winding, by connecting an output end of the V₁-phasewinding and an output end of the V₂-phase winding, and by connecting anoutput end of the W₁-phase winding and an output end of the W₂-phasewinding.

According to the present invention, the U₁₋₁-phase winding portion thatconstitutes the U₁-phase winding and the U₂₋₁-phase winding portion thatconstitutes the U₂-phase winding are wound into the first slot group,and the U₁₋₂-phase winding portion that constitutes the U₁-phase windingand the U₂₋₂-phase winding portion that constitutes the U₂-phase windingare wound into the second slot group. Thus, the number of conductorwires that are housed in each of the slots of the first slot group is(m+n), and the number of conductor wires that are housed in each of theslots of the second slot group is (m+n). Thus, the number of conductorwires that are housed in each of the slots is equal, suppressingformation of unevenness on inner circumferential surfaces of the coilend groups of the stator winding. Generation of wind-splitting noisethat results from interference between the rotating rotor and the innercircumferential surfaces of the coil end groups is thereby suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross section that shows an automotivealternator according to a preferred embodiment of the present invention;

FIG. 2 is an electrical circuit diagram for the automotive alternatoraccording to the preferred embodiment of the present invention;

FIG. 3 is a connection diagram for a stator winding in the automotivealternator according to the preferred embodiment of the presentinvention;

FIG. 4 is an end elevation that shows a stator core that is used in theautomotive alternator according to the preferred embodiment of thepresent invention;

FIG. 5 is a partial end elevation that explains a state in whichconductor wires are mounted into the stator core in the automotivealternator according to the preferred embodiment of the presentinvention;

FIG. 6 is a graph that shows measured results of output characteristicsof the automotive alternator according to the preferred embodiment ofthe present invention;

FIG. 7 is a connection diagram for a stator winding according to acomparative example; and

FIG. 8 is a partial end elevation that explains a state in whichconductor wires are mounted into a stator core in an automotivealternator according to the comparative example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will now be explainedwith reference to the drawings.

FIG. 1 is a longitudinal cross section that shows an automotivealternator according to a preferred embodiment of the present invention,FIG. 2 is an electrical circuit diagram for the automotive alternatoraccording to the preferred embodiment of the present invention, FIG. 3is a connection diagram for a stator winding in the automotivealternator according to the preferred embodiment of the presentinvention, FIG. 4 is an end elevation that shows a stator core that isused in the automotive alternator according to the preferred embodimentof the present invention, and FIG. 5 is a partial end elevation thatexplains a state in which conductor wires are mounted into the statorcore in the automotive alternator according to the preferred embodimentof the present invention. Moreover, 1, 7, etc., through 67 in FIG. 4represent slot numbers. FIG. 5 represents a state in which an annularstator core is cut open and spread out in a plane.

In FIG. 1, an automotive alternator 1 that functions as a rotaryelectric machine includes: a housing 4 that is constituted by a frontbracket 2 and a rear bracket 3 that are each approximately bowl-shapedand made of aluminum; a shaft 6 that is rotatably supported in thehousing 4 by means of bearings 5; a pulley 7 that is fixed to an endportion of the shaft 6 that extends out frontward from the housing 4; arotor 8 that is fixed to the shaft 6 and that is disposed inside thehousing 4; a stator 20 that is fixed to the housing 4 so as to surroundthe rotor 8; a pair of slip rings 12 that are fixed to a rear end of theshaft 6, and that supply electric current to the rotor 8; a pair ofbrushes 13 that slide on respective surfaces of the slip rings 12; abrush holder 14 that accommodates the brushes 13; a rectifier 15 that iselectrically connected to the stator 20 so as to convert alternatingcurrent that is generated by the stator 20 into direct current; and avoltage regulator 16 that is mounted onto the brush holder 14, and thatadjusts magnitude of an alternating-current voltage that is generated bythe stator 20.

The rotor 8 includes: a field coil 9 that generates magnetic flux onpassage of an excitation current; a pole core 10 that is disposed so asto cover the field coil 9, and in which magnetic poles are formed by themagnetic flux; and the shaft 6, which is fitted centrally through thepole core 10. Fans 11 are fixed to two axial end surfaces of the polecore 10 by welding, etc.

The stator 20 is held from two axial ends by the front bracket 2 and therear bracket 3, and includes: a stator core 21 that is disposed so as tosurround the pole core 10 so as to ensure a uniform gap from an outerperipheral surface of the pole core 10 of the rotor 8; and the statorwinding 22, which is mounted to the stator core 21.

As shown in FIG. 4, the stator core 21 is a laminated core that isformed into a cylindrical shape by laminating a predetermined number ofcore segments that are formed by punching thin magnetic steel platesinto annular shapes, and integrating the laminated predetermined numberof core segments by welding, for example. The stator core 21 has: anannular core back portion 21 a; tooth portions 21 b that each extendradially inward from an inner peripheral surface of the core backportion 21 a, and that are arranged at a uniform angular pitchcircumferentially; and slots 21 c that are bounded by the core backportion 21 a and adjacent tooth portions 21 b.

Here, the number of claw-shaped magnetic poles in the pole core 10 ofthe rotor 8 is twelve, and the number of slots 21 c is seventy-two.Specifically, the slots 21 c are formed at a ratio of two slots perphase per pole, and at a uniform angular pitch circumferentially (anelectrical pitch of π/6).

As shown in FIGS. 2 and 3, the stator winding 22 is configured byconnecting together output ends of the three phases of the firstthree-phase stator winding 23 and the second three-phase stator winding24 to connect the first three-phase stator winding 23 and the secondthree⁻phase stator winding 24 in parallel.

The first three-phase stator winding 23 is configured by wye-connectinga U₁-phase winding 30, a V₁-phase winding 31, and a W₁-phase winding 32.The U₁-phase winding 30 is configured by connecting in series aU₁₋₁-phase winding portion 41 and a U₁₋₂-phase winding portion 42 thathave a phase difference of 30 electrical degrees. The V₁-phase winding31 is configured by connecting in series a V₁₋₁-phase winding portion 43and a V₁₋₂-phase winding portion 44 that have a phase difference of 30electrical degrees. The W₁-phase winding 32 is configured by connectingin series a W₁₋₁-phase winding portion 45 and a W₁₋₂-phase windingportion 46 that have a phase difference of 30 electrical degrees.

The second three-phase stator winding 24 is configured by wye-connectinga U₂-phase winding 35, a V₂-phase winding 36, and a W₂-phase winding 37.The U₂-phase winding 35 is configured by connecting in series aU₂₋₁-phase winding portion 51 and a U₂₋₂-phase winding portion 52 thathave a phase difference of 30 electrical degrees. The V₂-phase winding36 is configured by connecting in series a V₂₋₁-phase winding portion 53and a V₂₋₂-phase winding portion 54 that have a phase difference of 30electrical degrees. The W₂-phase winding 37 is configured by connectingin series a W₂₋₁-phase winding portion 55 and a W₂₋₂-phase windingportion 56 that have a phase difference of 30 electrical degrees.

An output end of the U₁-phase winding 30 and an output end of theU₂-phase winding 35 are connected, an output end of the V₁-phase winding31 and an output end of the V₂-phase winding 36 are connected, and anoutput end of the W₁-phase winding 32 and an output end of the W₂-phasewinding 37 are connected. The first three-phase stator winding 23 andthe second three-phase stator winding 24 are thereby connected inparallel to configure the stator winding 22.

Next, a specific construction of the stator winding 22 will beexplained.

The U₁₋₁-phase winding portion 41 is a three-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in a firstslot group that is constituted by the slots 21 c at intervals of sixslots that include Slot Numbers 1, 7, etc., through 61, and 67. TheU₁₋₂-phase winding portion 42 is a four-turn wave winding that is formedby winding a conductor wire 29 into a wave winding in a second slotgroup that is constituted by the slots 21 c at intervals of six slotsthat include Slot Numbers 2, 8, etc., through 62, and 68.

The V₁₋₁-phase winding portion 43 is a three-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in a thirdslot group that is constituted by the slots 21 c at intervals of sixslots that include Slot Numbers 3, 9, etc., through 63, and 69. TheV₁₋₂-phase winding portion 44 is a four-turn wave winding that is formedby winding a conductor wire 29 into a wave winding in a fourth slotgroup that is constituted by the slots 21 c at intervals of six slotsthat include Slot Numbers 4, 10, etc., through 64, and 70.

The W₁₋₁-phase winding portion 45 is a three-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in a fifthslot group that is constituted by the slots 21 c at intervals of sixslots that include Slot Numbers 5, 11, etc., through 65, and 71. TheW₁₋₂-phase winding portion 46 is a four-turn wave winding that is formedby winding a conductor wire 29 into a wave winding in a sixth slot groupthat is constituted by the slots 21 c at intervals of six slots thatinclude Slot Numbers 6, 12, etc., through 66, and 72.

The U₂₋₁-phase winding portion 51 is a four-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in the firstslot group. The U₂₋₂-phase winding portion 52 is a three-turn wavewinding that is formed by winding a conductor wire 29 into a wavewinding in the second slot group.

The V₂₋₁-phase winding portion 53 is a four-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in the thirdslot group. The V₂₋₂-phase winding portion 54 is a three-turn wavewinding that is formed by winding a conductor wire 29 into a wavewinding in the fourth slot group.

The W₂₋₁-phase winding portion 55 is a four-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in the fifthslot group. The W₂₋₂-phase winding portion 56 is a three-turn wavewinding that is formed by winding a conductor wire 29 into a wavewinding in the sixth slot group.

The U₁-phase winding 30 is configured by joining a winding finishportion of the U₁₋₁-phase winding portion 41 and a winding start portionof the U₁₋₂-phase winding portion 42 by tungsten-inert gas (TIG)welding, etc., and is a seven-turn winding. Similarly, the V₁-phasewinding 31 and the W₁-phase winding 32 are also seven-turn wavewindings. Then, the winding start portions of the U₁₋₁-phase windingportion 41, the V₁₋₁-phase winding portion 43, and the W₁₋₁-phasewinding portion 45 are joined by TIG welding, etc., to form the firstthree-phase stator winding 23.

The U₂-phase winding 35 is a seven-turn wave windings that is configuredby connecting the U₂₋₁-phase winding portion 51 and the U₂₋₂-phasewinding portion 52 in series. Similarly, the V₂-phase winding 36 and theW₂-phase winding 37 are also seven-turn wave windings. Then, the windingstart portions of the U₂₋₁-phase winding portion 51, the V₂₋₁-phasewinding portion 53, and the W₂₋₁-phase winding portion 55 are joined byTIG welding, etc., to form the second three-phase stator winding 24.

In addition, winding finish portions of the U₁₋₂-phase winding portion42 and the U₂₋₂-phase winding portion 52 are joined by TIG welding,etc., winding finish portions of the V₁₋₂-phase winding portion 44 andthe V₂₋₂-phase winding portion 54 are joined by TIG welding, etc., andwinding finish portions of the W₁₋₂-phase winding portion 46 and theW₂₋₂-phase winding portion 56 are joined by TIG welding, etc., to formthe stator winding 22.

Next, operation of the automotive alternator 1 that is configured inthis manner will be explained.

First, an electric current is supplied from a battery (not shown)through the brushes 13 and the slip rings 12 to the field coil 9 of therotor 8 to generate magnetic flux. Magnetic poles are formed in theclaw-shaped magnetic poles of the pole core 10 by this magnetic flux.

At the same time, rotational torque from an engine is transferred to theshaft 6 by means of a belt (not shown) and the pulley 7 to rotate therotor 8. Thus, rotating magnetic fields are applied to the statorwinding 22 in the stator 20 to generate electromotive forces in thestator winding 22. The alternating currents that are generated by theseelectromotive forces are rectified into a direct current by therectifier 15, to charge the battery, or be supplied to an electricalload.

In the stator winding 22 that is configured in this manner, the twowinding portions of each of the phases that are connected in parallelall have seven turns, suppressing the generation of cyclic currents inthe parallel circuit portions.

As shown in FIG. 5, seven conductor wires 29 are housed inside each ofthe slots 21 c. Thus, the number of conductor wires 29 that are housedin each of the slots 21 c is equal, suppressing the formation ofunevenness on the inner circumferential surfaces of the coil end groupsof the stator winding 22. Generation of wind-splitting noise thatresults from interference between the rotating rotor 8 and the innercircumferential surfaces of the coil end groups is thereby suppressed.

Because the neutral points between the first three-phase stator winding23 and the second three-phase stator winding 24 are each configured byconnecting three conductor wires 29, work for connecting together theneutral points between the first three-phase stator winding 23 and thesecond three-phase stator winding 24 is extremely complicated. In thepresent invention, because the neutral points between the firstthree-phase stator winding 23 and the second three-phase stator winding24 are not connected with each other, the complicated connecting workcan be omitted, facilitating manufacturing of the stator 20.

In the respective phase windings, because two winding portions that areoffset by 30 electrical degrees, such as the U₁₋₁-phase winding portion41 and the U₁₋₂-phase winding portion 42, for example, are connected inseries, magnetomotive pulsating forces can be reduced, reducing magneticnoise.

In the respective phase windings, because the turn counts in the twowinding portions that are connected in series, such as the U₁₋₁-phasewinding portion 41 and the U₁₋₂-phase winding portion 42, for example,are different, output from the automotive alternator 1 can be increased.

Here, results when output characteristics of the present automotivealternator 1 were measured are shown in FIG. 6. Moreover, in FIG. 6, thesolid line represents the output characteristics of the presentautomotive alternator 1, and the broken line represents the outputcharacteristics of a comparative automotive alternator. The comparativeautomotive alternator is configured in a similar manner to that of thepresent automotive alternator 1 except that a comparative stator winding60 that is shown in FIG. 7 is used.

As can be seen from FIG. 6, it has been confirmed that the automotivealternator 1 can achieve higher output than the comparative automotivealternator throughout a range of rotational speeds.

Next, a specific construction of the comparative stator winding 60 willbe explained with reference to FIGS. 7 and 8. Moreover, FIG. 7 is aconnection diagram for a stator winding according to the comparativeexample, and FIG. 8 is a partial end elevation that explains a state inwhich conductor wires are mounted into a stator core in an automotivealternator according to the comparative example. Moreover, FIG. 8represents a state in which an annular stator core is cut open andspread out in a plane.

A U₁₋₁-phase winding portion 71 is a four-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in the firstslot group. A U₁₋₂-phase winding portion 72 is a three-turn wave windingthat is formed by winding a conductor wire 29 into a wave winding in thesecond slot group.

A V₁₋₁-phase winding portion 73 is a four-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in the thirdslot group. A V₁₋₂-phase winding portion 74 is a three-turn wave windingthat is formed by winding a conductor wire 29 into a wave winding in thefourth slot group.

A W₁₋₁-phase winding portion 75 is a four-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in the fifthslot group. A W₁₋₂-phase winding portion 76 is a three-turn wave windingthat is formed by winding a conductor wire 29 into a wave winding in thesixth slot group.

A U₂₋₁-phase winding portion 81 is a four-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in the firstslot group. A U₂₋₂-phase winding portion 82 is a three-turn wave windingthat is formed by winding a conductor wire 29 into a wave winding in thesecond slot group.

A V₂₋₁-phase winding portion 83 is a four-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in the thirdslot group. A V₂₋₂-phase winding portion 84 is a three-turn wave windingthat is formed by winding a conductor wire 29 into a wave winding in thefourth slot group.

A W₂₋₁-phase winding portion 85 is a four-turn wave winding that isformed by winding a conductor wire 29 into a wave winding in the fifthslot group. A W₂₋₂-phase winding portion 86 is a three-turn wave windingthat is formed by winding a conductor wire 29 into a wave winding in thesixth slot group.

A U-phase winding 61 is configured by connecting in series a windingportion in which the U₁₋₁-phase winding portion 71 and the U₂₋₁-phasewinding portion 81 are connected in parallel and a winding portion inwhich the U₁₋₂-phase winding portion 72 and the U₂₋₂-phase windingportion 82 are connected in parallel. A V-phase winding 62 is configuredby connecting in series a winding portion in which the V₁₋₁-phasewinding portion 73 and the V₂₋₁-phase winding portion 83 are connectedin parallel and a winding portion in which the V₁₋₂-phase windingportion 74 and the V₂₋₂-phase winding portion 84 are connected inparallel. A W-phase winding 63 is configured by connecting in series awinding portion in which the W₁₋₁-phase winding portion 75 and theW₂₋₁-phase winding portion 85 are connected in parallel and a windingportion in which the W₁₋₂-phase winding portion 76 and the W₂₋₂-phasewinding portion 86 are connected in parallel.

As shown in FIG. 7, the stator winding 60 is configured bywye-connecting the U-phase winding 61, the V-phase winding 62, and theW-phase winding 63, and forms an electrical circuit that isapproximately equivalent to that of the stator winding 22 describedabove.

The comparative automotive alternator is configured using the statorwinding 60 instead of the stator winding 22. In the stator winding 60that is configured in this manner, the turn counts of the two windingportions that constitute the respective parallel circuit portions arealso equal, suppressing the generation of cyclic currents in theparallel circuit portions. Because two winding portions that are offsetby 30 electrical degrees are connected in series in each of the phasewindings, magnetomotive pulsating forces can be reduced, reducingmagnetic noise.

However, in the automotive alternator according to the comparativeexample, slots 21 c in which eight conductor wires 29 are housed andslots 21 c in which six conductor wires 29 are housed are arrangedalternately, as shown in FIG. 8. Thus, unevenness arises on the innercircumferential surface of the coil end groups of the stator winding 22,increasing wind-splitting noise that results from interference betweenthe rotating rotor 8 and the inner circumferential surfaces of the coilend groups.

Moreover, in each of the above embodiments, explanations are given forautomotive alternators, but the present invention is not limited toautomotive alternators, and similar effects are also exhibited if thepresent invention is applied to automotive rotary electric machines suchas automotive electric motors, automotive generator-motors, etc.

In the above embodiment, phase windings are configured by connecting inseries two winding portions that have a phase difference of 30electrical degrees, but the phase difference between the two windingportions that are connected in series is not limited to 30 (electrical)degrees.

In the above embodiment, respective phase windings of the first andsecond three-phase stator windings are configured by connecting afour-turn winding portion and a three-turn winding portion in series,but the turn counts of the two winding portions that are connected inseries are not limited to four turns and three turns, provided that theyare different than each other.

1. A rotary electric machine comprising: a rotor that is rotatably supported by a housing; and a stator comprising: a stator core in which slots are formed at a ratio of two slots per phase per pole; and a first three-phase stator winding and a second three-phase stator winding that are mounted into said stator core, said stator being supported by said housing so as to surround said rotor, wherein: said first three-phase stator winding is configured by wye-connecting a U₁-phase winding, a V₁-phase winding, and a W₁-phase winding; said second three-phase stator winding is configured by wye-connecting a U₂-phase winding, a V₂-phase winding, and a W₂-phase winding; said U₁-phase winding is configured by connecting a U₁₋₁-phase winding portion and a U₁₋₂-phase winding portion in series; said V₁-phase winding is configured by connecting a V₁₋₁-phase winding portion and a V₁₋₂-phase winding portion in series; said W₁-phase winding is configured by connecting a W₁₋₁-phase winding portion and a W₁₋₂-phase winding portion in series; said U₂-phase winding is configured by connecting a U₂₋₁-phase winding portion and a U₂₋₂-phase winding portion in series; said V₂-phase winding is configured by connecting a V₂₋₁-phase winding portion and a V₂₋₂-phase winding portion in series; said W₂-phase winding is configured by connecting a W₂₋₁-phase winding portion and a W₂₋₂-phase winding portion in series; said U₁₋₁-phase winding portion and said U₂₋₁-phase winding portion are mounted into a first slot group that is constituted by said slots at intervals of six slots; said U₁₋₂-phase winding portion and said U₂₋₂-phase winding portion are mounted into a second slot group that is constituted by said slots at intervals of six slots and that is adjacent to said first slot group; said V₁₋₁-phase winding portion and said V₂₋₁-phase winding portion are mounted into a third slot group that is constituted by said slots at intervals of six slots; said V₁₋₂-phase winding portion and said V₂₋₂-phase winding portion are mounted into a fourth slot group that is constituted by said slots at intervals of six slots and that is adjacent to said third slot group; said W₁₋₁-phase winding portion and said W₂₋₁-phase winding portion are mounted into a fifth slot group that is constituted by said slots at intervals of six slots; said W₁₋₂-phase winding portion and said W₂₋₂-phase winding portion are mounted into a sixth slot group that is constituted by said slots at intervals of six slots and that is adjacent to said fifth slot group; said U₁₋₁-phase winding portion, said U₂₋₂-phase winding portion, said V₁₋₁-phase winding portion, said V₂₋₂-phase winding portion, said W₁₋₁-phase winding portion, and said W₂₋₂-phase winding portion are configured by winding conductor wires that have an identical cross-sectional shape into respective wave windings in said slots at intervals of six slots for m turns (where m is an integer); said U₁₋₂-phase winding portion, said U₂₋₁-phase winding portion, said V₁₋₂-phase winding portion, said V₂₋₁-phase winding portion, said W₁₋₂-phase winding portion, and said W₂₋₁-phase winding portion are configured by winding said conductor wires into respective wave windings in said slots at intervals of six slots for n turns (where n is an integer that is different than m); and said first three-phase stator winding and said second three-phase stator winding are connected in parallel by connecting an output end of said U₁-phase winding and an output end of said U₂-phase winding, by connecting an output end of said V₁-phase winding and an output end of said V₂-phase winding, and by connecting an output end of said W₁-phase winding and an output end of said W₂-phase winding.
 2. A rotary electric machine according to claim 1, wherein a neutral point of said first three-phase stator winding and a neutral point of said second three-phase stator winding are not connected. 